Proteolytic activity in cod (Gadus morhua) muscle during salt curing

The proteolytic activity of alkaline and acidic proteases in muscle from cod (Gadus morhua) was determined during salt curing. Proteolytic activity was determined for cod muscle that was either ice-stored or frozen-stored before it was subjected to three different salt treatments. The activity of the proteases chymotrypsin, trypsin, collagenase, elastase and cathepsin B/L was determined by the use of different fluorogenic substrates, while the total activity of acidic proteases was determined using haemoglobin as a substrate. The results indicated that the activity of the chymotrypsin, trypsin, collagenase and elastase was stimulated with increasing salt concentration, but seemed to decline again as the salt curing proceeded. Haemoglobin-hydrolysing activities, however, seemed to decrease with increasing concentration of salt in the muscle tissue.